Vitamin C and A1c Relationship in the National Health and Nutrition Examination Survey (NHANES) 2003-2006

J Am Coll Nutr. 2011 Dec;30(6):477-83. doi: 10.1080/07315724.2011.10719993.


Objective: The scope of the diabetes epidemic stresses the critical need for primary prevention. The consumption of foods high in vitamin C has been associated with lower risk of diabetes. The aim of this study was to analyze the relation between vitamin C concentration and glycemic control index in a large sample of U.S. adults without a history of diabetes.

Methods: We analyzed data collected from 7697 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 who did not report a history of diabetes. Multivariate linear regression analyzed the association of vitamin C and hemoglobin A1c (A1c) levels after accounting for potential confounders. We also conducted stratified analyses based on race/ethnicity, gender, age group, body mass index, and vitamin D status.

Results: Vitamin C concentrations were inversely associated with A1c (p = 0.0202). Stronger inverse associations were observed in subjects 18-44 years of age (p = 0.0017), as well as in female (p = 0.0035) and Mexican American (p = 0.0149) subgroups. Evidence of a significant interaction between vitamin C and vitamin D was noted in subjects aged 18-44 years and in females (p = 0.0073 and 0.0095 respectively), with the inverse association tending to be evident at lower levels of vitamin D.

Conclusions: Vitamin C status may influence glycemic control. Investigators should be cognizant of the interaction of vitamins C and D and should take this into consideration in planning future studies.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Ascorbic Acid / analysis
  • Ascorbic Acid / metabolism*
  • Blood Glucose / analysis
  • Body Mass Index
  • Cross-Sectional Studies
  • Diabetes Mellitus / prevention & control
  • Female
  • Glycated Hemoglobin A / analysis
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Linear Models
  • Male
  • Mexican Americans / statistics & numerical data
  • Middle Aged
  • Multivariate Analysis
  • Nutrition Surveys*
  • Vitamin D / analysis
  • Vitamin D / metabolism
  • Young Adult


  • Blood Glucose
  • Glycated Hemoglobin A
  • Vitamin D
  • Ascorbic Acid